Abstract not found

The growing popularity of aspect-oriented languages, such as AspectJ, and of corresponding design approaches, makes it important to learn how best to modularize programs in which aspect-oriented composition mechanisms are used. We contribute an approach to information hiding modularity in programs that use quantified advising as a module composition mechanism. Our approach rests on a new kind of interface: one that abstracts a crosscutting behavior, decouples the design of code that advises such a behavior from the design of the code to be advised, and that can stipulate behavioral contracts. Our interfaces establish design rules that govern how specific points in program execution are exposed through a given join point model and how conforming code on either side should behave. In a case study of the HyperCast overlay network middleware system, including a real options analysis, we compare the widely cited oblivious design approach with our own, showing significant weaknesses in the former and benefits in the latter.

This paper proposes language concepts that facilitate the separation of an application into independent reusable building blocks and the integration of pre-build generic software components into applications that have been developed by third party vendors. A key element of our approach are ondemand remodularizations, meaning that the abstractions and vocabulary of an existing code base are translated into the vocabulary understood by a set of components that are connected by a common collaboration interface. This general concept allows us to mix-and-match remodularizations and components on demand.

Implementation

. In this paper we deal with object-oriented component integration issues. We argue that traditional framework customization techniques are inappropriate for componentbased programming since they lack support for non-invasive, encapsulated, dynamic customization. We propose a new language construct, called a pluggable composite adapter, for expressing component gluing. A pluggable composite adapter allows the separation of customization code from component implementation, resulting in better modularity, flexible extensibility, and improved maintenance and understandability. We also discuss alternative realizations of the construct. 1. Introduction Component software, i.e., software that is an assembly of individual, independently developed parts, is becoming the predominant architecture. We consider two factors as the driving force behind this development. First, as indicated in [22] component software represents a middle path between the two extremes that predominate traditional sof...

Recent developments in service architectures suggest that run-time adaptations could be implemented with dynamic AOP. In this paper we discuss application requirements on run-time AOP support and present a system that addresses these requirements. We provide basic support for weaving using the Just-In-Time compiler, while the AOP system is treated as an exchangeable module on top of the basic support. This approach allows us to provide a low run-time overhead, AOP system exibility, and secure weaving. We provide an extensive empirical evaluation and discuss the trade-o s resulting from using the JIT compiler and a modularized architecture.

Virtual classes are class-valued attributes of objects. Like virtual methods, virtual classes are defined in an object’s class and may be redefined within subclasses. They resemble inner classes, which are also defined within a class, but virtual classes are accessed through object instances, not as static components of a class. When used as types, virtual classes depend upon object identity – each object instance introduces a new family of virtual class types. Virtual classes support large-scale program composition techniques, including higher-order hierarchies and family polymorphism. The original definition of virtual classes in BETA left open the question of static type safety, since some type errors were not caught until runtime. Later the languages Caesar and gbeta have used a more strict static analysis in order to ensure static type safety. However, the existence of a sound, statically typed model for virtual classes has been a long-standing open question. This paper presents a virtual class calculus, vc, that captures the essence of virtual classes in these full-fledged programming languages. The key contributions of the paper are a formalization of the dynamic and static semantics of vc and a proof of the soundness of vc. Categories and Subject Descriptors D.3.3 [Language Constructs and Features]: Classes and objects, inheritance, polymorphism; F.3.3 [Studies of Program Constructs]: Object-oriented constructs,

Most software systems are inflexible. Reconfiguring a system’s modules to add or to delete a feature requires substantial effort. This inflexibility increases the costs of building variants of a system, amongst other problems. New languages and tools that are being developed to provide additional support for separating concerns show promise to help address this problem. However, applying these mechanisms requires determining how to enable a feature to be separated from the codebase. In this paper, we investigate this problem through an exploratory study conducted in the context of two existing systems: gnu.regexp and jFTPd. The study consisted of applying three different separation of concern mechanisms—Hyper/J, TM AspectJ, TM and a lightweight, lexically-based approach—to separate features in the two packages. In this paper, we report on the study, providing contributions in two areas. First, we characterize the effect different mechanisms had on the structure of the codebase. Second, we characterize the restructuring process required to perform the separations. These characterizations can help researchers to elucidate how the mechanisms may be best used, tool developers to design support to aid the separation process, and early adopters to apply the techniques.

Abstract not found

The fact that crosscutting concerns (aspects) cannot be well modularized in object oriented software is an impediment to program comprehension: the implementation of a concern is typically scattered over many locations and tangled with the implementation of other concerns, resulting in a system that is hard to explore and understand. Aspect mining aims to identify crosscutting concerns in a system, thereby improving the system’s comprehensibility and enabling migration of existing (object-oriented) programs to aspect-oriented ones. In this paper, we compare three aspect mining techniques that were developed independently by different research teams: fan-in analysis, identifier analysis and dynamic analysis. We apply each technique to the same case (JHotDraw) and mutually compare the individual results of each technique based on the discovered aspects and on the level of detail and quality of those aspects. Strengths, weaknesses and underlying assumptions of each technique are discussed, as well as their complementarity. We conclude with a discussion of possible ways to combine the techniques in order to achieve a better overall aspect-mining technique.